What is Contact: Definition and 447 Discussions

Contact dermatitis is a type of inflammation of the skin. Some symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, and swelling. The rash isn't contagious or life-threatening, but it can be very uncomfortable.
Contact dermatitis results from either exposure to allergens (allergic contact dermatitis) or irritants (irritant contact dermatitis). Phototoxic dermatitis occurs when the allergen or irritant is activated by sunlight. Diagnosis of allergic contact dermatitis can often be supported by patch testing.

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  1. S

    Earth Day - My Contact Experience

    Before I begin, immediately after I saw my first two sightings and after reporting them to nuforc and mufon, I started refining my experience by writing thoughts down to the best degree humanly possible. Take in consideration, what I saw was not supposed to exist and I am describing how it...
  2. M

    Contact Stress - Can we add it up?

    I have calculated the contact stress for a sphere in a socket using formulas provided in Roark's formulas. But my problem is that the sphere is actually in contact with two sockets - upper and lower sides, so there are actually two contact areas. Can I just multiply the contact stress I...
  3. B

    The effects of electrical shock on the brain from non-localized contact area

    In my attempt to obliterate my ignorance I'd like to discuss something related to the recent news story about a young man who attached two clamps to his nipples and then had a friend plug it into a wall socket. http://news.gather.com/viewArticle.action?articleId=281474978486647" <-- News Story...
  4. M

    Alien Contact & the Drake Equation: Agree or Disagree?

    I recently made my first blog post on the subject of whether http://reptoavian.blogspot.com/2010/08/alien-contact-forthcoming.html" . Do you agree or disagree with my estimates of the variables in the Drake equation? What do you think of my conclusions for the number and spacing between...
  5. W

    Wheel torque > contact patch friction > torque

    Am I correct in saying that when a torque is applied to a wheel the force is resisted by the friction at the contact patch and then becomes a "equal and opposite" torque acting around the contact patch?
  6. H

    Could Passive Marijuana Smoke Make Me Dumber? Help!

    Hello I just moved in with some new people who, I have found out, smoke a lot of weed. Now the internet is full of info about how passive smoking can explain a positive drug test but this is not what I'm interested in. I'm afraid I could get dumber from the passive smoke inhalation. If that's...
  7. B

    Modeling Sandwich Composites in Workbench: Non-Penalty Based Contact?

    When I model a honeycomb type composite in workbench I tired modeling the core material as an orthogonal material type using solid tet elements and the aluminum face sheets as isotropic shell elements. I base the core material properties off of the honeycomb manufactures data for stiffness...
  8. S

    Forces - two objects in contact

    Homework Statement Two objects, in contact with each other, are being pushed across a table. The masses are 113g and 139g. Friction is negligible. The applied horizontal force of magnitude 0.0538N is exerted on the more massive object. Determine the acceleration of the two object system and...
  9. K

    Fresh water and contact lenses

    I kitesurf a lot in both fresh water and salt water. I wear well-fitting contact lenses that do not shift around or come out, even if I rub my eyes. In SALT WATER: I can crater from 20 feet in the air with a thunderous crash and get dragged through and tumbled by waves with my eyes open...
  10. E

    Determining parameters for trapped air in contact with water.

    Hi everyone, I need to evaluate parameters (heat capacity, density and thermal conductivity) for some very humid air. I know the parameters for both dry air and water vapor. So I suppose the parameters I need will just be a linear combination of the other parameters, with a coefficient...
  11. B

    Calculating Normal Reaction & Contact Force on 800kg Van Attached to Car

    Homework Statement The following camping van with a total mass of 800 kg is connected at point P to the back of a car. The car accelerates with constant acceleration a during 4 seconds from rest until it achieves 60 km/h. Assuming there is no resistance (from air and ground), calculate the...
  12. I

    Newtons Law and Friction Question (along with a contact force question)

    Homework Statement Two crates, of mass 75 kg and 110 kg are in contact and at rest on a horizontal surface. A 620N force is exerted on the 75 kg crate. If the coefficient of kinetic friction is 0.15 calculate: a) the acceleration of the system b)the force that each crate exerts on the...
  13. D

    Perfectly Rough Contact: Exploring Surface Interactions

    What does it mean for the contact between two surfaces to be "perfectly rough"?
  14. G

    What happens when two charged spheres are brought into contact?

    When a metal sphere, A, with a charge of +5q is touched to a sphere,B, with a charge of -q what would each of the spheres charge would be and what would there the circle view of the final sphere? thanks
  15. U

    Contact Process: SO3 Not Absorbed in Water

    Homework Statement SO3 is not absorbed in water directly to form sulfuric acid because A. Reaction doesn't go to completion B. Reaction is slow. C. Highly exothermic. D. Insoluble Homework Equations -------------- The Attempt at a Solution MY...
  16. T

    Schools Applied to grad school should I contact potential supervisors?

    I recently applied to some grad schools for a PhD program and I was notified by one particular school that while my marks were under their admission requirements, they recognize that I have valuable background experience which may allow me to succeed and that they would circulate my file to...
  17. J

    Magnitude of contact force?

    1. A student who's standing still on level ground weights 570 N and is wearing a backpack that is 81 N. a) What's the magnitude of net force on the student? b) What's the magnitude of the contact force on the student by the backpack? c) What's the magnitude of the contact foce on the...
  18. J

    Acceleration and magnitude of contact force

    Two blocks of masses m1 = 4.00 kg and m2 = 3.00 kg are placed in contact with each other on a frictionless horizontal surface. A constant force F = 9.00 N is applied to the block of mass m1. a) Determine the magnitude of the acceleration of the two-block system. b) Determine the magnitude of...
  19. CFDFEAGURU

    ANSYS RBE3 command vs Contact Wizard

    Hello all, Just thought I would throw this one out there. Who preferes to use the RBE3 command to automatically create a set of constraint equations and who prefers to use the Contact Wizard? I used to use the Contact Wizard but I recently got burned by it, so I switched to using the...
  20. I

    Contactor with auxillary contact

    Hi, i want to make automatic on/off the pump with float switch for my tank with contactor(with auxillary contact) i have, 1. contactor with auxillary contacts 2. Float switch 3. Manual On/Off switch for pump i want the connection details according to attached diagram. Thanks.
  21. S

    Hertz Contact Stress for static condition

    Hi all, I am designing a set of side guide rollers for a vertical gate. There are four rollers on the gate (two on each side), and the rollers are designed for jamming load condition (they are not loaded most of the time). When jamming happens, one top roller and one bottom roller (on the...
  22. N

    Scenario of gamma ray bursts if it were to come into contact with the earth's ozone

    Is there a video of that kind of scenario floating around youtube? Have not had any luck finding a video of such a scenario.
  23. A

    Temperature dependence of contact angle in liquids

    How does contact angle change with temperature and why? Does capillary rise have a temperature dependence?
  24. C

    Contact Lens: How to focus light 1mm away

    So, I've been wondering. Anyone know what shape/prescription a contact lens would have to be in order for an eye to be able to focus on something 1mm away (assuming the distance of focus in the eye is around 4 cm)? Does it have to do with focal length of the lens?
  25. B

    Average acceleration of a falling ball on contact with floor

    Homework Statement A ball falls on the surface from 10m height and rebounds to 2.5m.If duration of contact with floor is 0.01 sec,then average acceleration during contact is- g = 10m/s^2 Homework Equations \alpha = \frac{v_2 + v_1}{t} The Attempt at a Solution Now here v_{1}...
  26. H

    Thermal Equilibrium of Blocks In Contact -

    Homework Statement A nano particle consisting of four iron atoms (object 1) initially has 1 quantum of energy. It is brought into contact with another nano particle, consisting of two iron atoms (object 2), which has 2 quanta of energy. The mass of one mole of iron is 56 gram. a...
  27. T

    Newton's laws multiple objects contact forces

    Homework Statement Three crates are arranged. Their masses are m1=29.8, m2= 15.3, m3= 27.3. The applied force of 910 N is directed horizontally and the coefficient of friction is u= .277 WHAT IS THE MAGNITUDE OF THE CONTACT FORCE BETWEEN M1 and M2? WHAT IS THE MAGNITUDE OF THE CONTACT...
  28. D

    Contact lenses, focal length and uncorrected far point distance

    1. A nearsighted person wears contacts with a focal length of -7.6cm. If this person's far point distance with her glasses is 8.7m, what is her uncorrected far point distance? 2. 1/F=1/do+1/di 3. 1/-7.6=1/do+1/870 =-7.534 I am completely lost here...please help. Thanks!
  29. P

    Elastic Collision: Contact Time?

    Homework Statement A handball of mass 668 grams is thrown straight against a wall with a speed of 13.36 m/s. It rebounds straight back out with the same speed. The average force exerted on the wall by the ball is 12 N. How long is the ball in contact with the wall? Homework Equations...
  30. D

    How Much Weight Must Block C Have to Prevent Block A from Sliding?

    blocks A and B have weights of 45 N and 25 N, respectively. block A is sitting on a table and block B is attached to block A by a piece of string on a frictionless pulley and block B is hanging off the table. also block C is on top of block A Figure 6-48 (a) Determine the...
  31. S

    What happens when olivine comes in contact with a SiO2 rich melt?

    im studying for an exam and this question came up anyone know what happens?
  32. V

    Transfer of torque - wheel to wheel contact

    Hi all, I am trying to calculate the the torque of a system which uses various size wheels to transfer power. Explained: A motor, of 100Nm torque, 40000 rpm, has a shaft of 7mm diameter in contact with a wheel 20mm in diameter. This wheel is in contact with a 15mm wheel. I need to...
  33. T

    Object Conceptualization Help Needed - Contact TDYOUNG24@HOTMAIL.COM

    How are you? I was conceptualizing some objects and found a particular base concept. I need help finishing it. Contact me at TDYOUNG24@HOTMAIL.COM thank you
  34. D

    Calculating Contact Forces for Pushing Boxes

    I've looked everywhere to find how do you calculate contact forces, like if you were pushing boxes. Don't want the answer just need to know how to do the calculations.
  35. H

    Find average force during contact when ball hits wall.

    A tennis ball has a mass of 0.057 kg. A professional tennis player hits the ball hard enough to give it a speed of 44 m/s (about 99 miles per hour.) The ball moves toward the left, hits a wall and bounces straight back to the right with almost the same speed (44 m/s). As indicated in the diagram...
  36. H

    Calculating the force at a single point of contact

    Hi all May be someone can help me with this problem. There is a isa-chrome60 wire (d=0.5 mm, tensile strength=600 N/mm^2) which is held at both ends using end connectors ( length of the wire = 20mm). And there is a nylon wire (d=0.5 mm) which is under tension (because of torsion spring)...
  37. F

    Hot Cold body in contact, what happens with heat and temperature?

    Homework Statement A hot body is brought into contact with a colder body until their temperatures are the same. Assume that no other bodies are around. 1.Is the heat lost by one body equal to the hear gained by the other? 2.Is the temp drop of one body equal to the temp increase of the...
  38. M

    Frictional force is independent of the area of contact

    one of the laws of friction states that the frictional force is independent of the area of contact,and velocity,how true is this? my book says this particular law is only approximately true.
  39. S

    Equations for surface-object contact.

    Hello there my fellow physics fans! I have decided to enter a national science competition in my potato obsessed homeland of Ireland called the "BT Young Scientist Awards". I am simply looking for clarification of the uniqueness of my project concept: I am planning on creating equations...
  40. K

    Net force on an object and contact force between objects

    Homework Statement "Three blocks (m1, m2 and m3) are in contact with each other on a frictionless, horizontal surface. A horizontal force is applied to m1. http://i4.photobucket.com/albums/y111/kathy_felldown/sb-pic0556.png What is the net force on block 1 and block 2? What is the...
  41. E

    Rigid body dynamics: Resting contact

    I'm currently programming a 2D rigid body dynamics engine. While I have realistic collision detection and response between polygons, I have trouble in the simulation once I implement gravity. When these rigid bodies are influenced by gravity, they never fall to complete rest (e.g. they...
  42. LydiaAC

    Point Contact Diode: Rectification Properties Explained

    Hello everybody: It is known that point contact diodes were an antecedent of PN junction diodes. I have read that they got their rectification properties from the fact that the metal in the point doped the semiconductor and formed a PN junction. However, it is known that you can rectify with...
  43. C

    Eye Contact with Dogs: Friend or Foe?

    Hi, I was wondering about the following. A friend (biologist) once told me that looking a cat in the eyes shows aggression, whereas making eye contact with a dog creates a kind of connection or bond. However, a quick Google search seems to indicate that also in canines, direct eye contact is...
  44. S

    How to contact faculty members?

    Hello, I am a senior and am planning to go to a physics gradschool. Looking at several forums and tips online, I came to know that it is good to contact faculty members of prospective gradschool. But I am not sure how to start the conversation, like what to talk about and how. What should i...
  45. I

    Hertzian contact stress SS-2244 / AISI-SAE 4140

    Hello guys! Is there anyone who knows where i can find information about maximum allowed Hertzian contact stress for material SS-2244 / AISI-SAE 4140 or any similar material quality? I have been searching for this information in several Swedish books and material tables, without success.
  46. P

    Focal length of her contact lenses

    Homework Statement Anne is farsighted; the nearest object she can see clearly without corrective lenses is 2.4 m away. It is 1.8 cm from the lens of her eye to the retina. What should the focal length of her contact lenses be so that she can see clearly objects as close as 24.0 cm from...
  47. O

    Contact Resistance Homework: Aluminium Contacts & Silicon Wafer

    Homework Statement Aluminium contacts {100} p-doped silicon (10ohm/square) which has been implanted into a 200mm wafer (1 mm thick) by 100keV phosphorus at 7X10^15. What will be the resistance of a 1um^2 contact and will it be ohmic? Homework Equations Rc = Pc/A The Attempt at a...
  48. maverick280857

    Band Diagram of a Metal-Semiconductor Contact

    Hi In the band diagram of an ideal Metal Semiconductor contact with \Phi_{M} < \Phi_{S} (work function of metal < work function of semiconductor) and a p-type semiconductor, why does the Fermi Level intersect the Intrinsic level right at the metallurgical junction? Thanks.
  49. M

    Two Mass In Contact On Slope

    Homework Statement Two packages at UPS start sliding down the 20° ramp shown in Figure P8.25. Package A has a mass of 5.0 kg and a *coefficient of friction of 0.20. Package B has a mass of 10 kg and a coefficient of friction of 0.15. How long does it take package A to reach the bottom? I...
  50. C

    Why Is Quantum Contact Conductance Maximized at 2*q^2/h Even Without Scattering?

    My question is how the maximum quantum contact conductance 2*q^2/h comes from. The maximum contact conductance can only be obtained when there is no scattering in the contacts between nano-channel and two big pads. (To my understanding, resistance comes from scattering, but if there is no...
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